bsnes/snesshader/Scale2x.OpenGL.shader

shader language=GLSL
	vertex~
		uniform vec2 rubyTextureSize;
		
		void main() {
			vec4 offsetx;
			vec4 offsety;
		
			gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
		
			offsetx.x = 1.0 / rubyTextureSize.x;
			offsetx.y = 0.0;
			offsetx.w = 0.0;
			offsetx.z = 0.0;
			offsety.y = 1.0 / rubyTextureSize.y;
			offsety.x = 0.0;
			offsety.w = 0.0;
			offsety.z = 0.0;
		
			gl_TexCoord[0] = gl_MultiTexCoord0;         //center
			gl_TexCoord[1] = gl_TexCoord[0] - offsetx;  //left
			gl_TexCoord[2] = gl_TexCoord[0] + offsetx;  //right
			gl_TexCoord[3] = gl_TexCoord[0] - offsety;  //top
			gl_TexCoord[4] = gl_TexCoord[0] + offsety;  //bottom
		}

	fragment~ filter=nearest
		uniform sampler2D rubyTexture;
		uniform vec2 rubyTextureSize;
		
		void main() {
			vec4 colD, colF, colB, colH, col, tmp;
			vec2 sel;
		
			col  = texture2DProj(rubyTexture, gl_TexCoord[0]);  //central (can be E0-E3)
			colD = texture2DProj(rubyTexture, gl_TexCoord[1]);  //D (left)
			colF = texture2DProj(rubyTexture, gl_TexCoord[2]);  //F (right)
			colB = texture2DProj(rubyTexture, gl_TexCoord[3]);  //B (top)
			colH = texture2DProj(rubyTexture, gl_TexCoord[4]);  //H (bottom)
		
			sel = fract(gl_TexCoord[0].xy * rubyTextureSize.xy);       //where are we (E0-E3)? E0 is default
		
			if(sel.y >= 0.5) { tmp = colB; colB = colH; colH = tmp; }  //E1 (or E3): swap B and H
			if(sel.x >= 0.5) { tmp = colF; colF = colD; colD = tmp; }  //E2 (or E3): swap D and F 
		
			if(colB == colD && colB != colF && colD != colH) {  //do the Scale2x rule
				col = colD;
			}

			gl_FragColor = col;
		}